It is well known in the electronic circuit board industry that it is necessary to remove the residue of the solder flux applied prior to the soldering operation during the manufacture of circuit boards. There are several proprietary solvent compositions employed by the industry to effectuate the removal of the flux. However, the removal of the residual flux is not a constant in the mechanized cleaning process and therefore tests have been devised to determine the effectiveness of the solvents used in the process to remove the flux residue. It is common to measure the conductivity of an alcohol-water test wash solution to determine the extent of the ionic constituents remaining on the boards after defluxing and, in the research laboratories, either infrared spectrophotometric analysis for qualitative analysis of the non-ionic constituents or high performance liquid chromatography to obtain quantitative analysis. The latter is a very expensive and complicated procedure due to the high cost of the analytical equipment necessary to carry out the test and the complicated procedure to be followed to insure the results are meaningful.
Therefore, it would be advantageous to the industry to have a relatively accurate yet simple test which can determine the extent of non-ionic constituents remaining on a board after cleaning to remove the flux.